Points of this type are often called focal points.[1] The idea is that on the boundary of Black's framework and White's framework, a play by Black will improve Black's framework and at the same time reduce or threaten White's framework.
Therefore these focal points are big points because they are double-purpose plays. They are often played in the opening as secondary big points (and are frequently the solution to whole-board problems with quiet positions).
See StrongGroups for an example and discussion.
Game played 1927-11-25: Go Seigen as Black played at 1 in reply to the marked white stone blocking off the side. This is considered both excellent timing, and a clear-sighted focal play (Black has no need to invade on the right).
Quite a move for a thirteen-year-old to come up with. Go Seigen was still in China at the time.
[1] Comment: That seems strange to me. There is nothing focal about such points. They are not at any focus, but at the frontier between moyos. I would call them frontier points or boundary points.
-- Bill
Charles Actually, as I now realise, such parts of the board should have many sector lines converging on them; in that sense they are focal or nodal.
Charles This terminology in English goes back a number of decades. Any Japanese or other term?
Bill: I usually see them referred to as tennozan, the name of a famous hill, which is also used to indicate a/the strategic point.
(Later): I see that the term, focal point, does not appear in the 2001 edition of the Go Players Almanac. Where does it appear in the go literature?
unkx80: I suspect tennozan is 天王山. =)
Bill: Yes. Thanks for the characters. :-)
unkx80: Then it is written exactly the same way in Chinese. =P
RobertoCorsini: I believe the term Focal Point refers to the simple fact that the move brings focus of the whole game into that area. It may not be a direct sente, but if left unanswered it will most likely prove to be a disaster. Thus, the one who makes a focal point move forces the opponent to do so as well - or find an even bigger move - possibly changing the course of the game.